These EXAIR Full Flow Air Knives were in need of an EXAIR Application Engineer’s expertise

Sometimes we get calls or emails from our customers that need help. Help can be in the form of product selection, heat load calculation, or proper installation. I had one such interaction with an end user of our Full Flow Air Knives, using them in the manner shown above.

The problem they were having was poor flow and low force from the blow off. We originally discussed the application over the phone, and after suspecting a plumbing issue may be at play, I asked for a photo. I received a quick photo of their setup and immediately saw the two knives were poorly plumbed. The clear/light blue hose, and the dark blue hoses in the photo just aren’t big enough for two knives of this size.

When installing any compressed air driven product, pressure and flow are the name of the game. Sometimes, as in this case, there was good pressure at the gauge (which, if checked at the inlet of the knife would have shown a significant pressure drop), but there just wasn’t enough flow. The root cause was diameter of the piping used to deliver the air from the main line to the point of use.

Once the compressed air line sizes were increased, the knives worked flawlessly and the end user could use them as intended – which was blowing debris off of a plate fed through the middle of the two knives.

In May of 1976, The Who performed a concert in London that Guiness’ Book of World Records used to certify them as the World’s Loudest Band. A sound level of 126 decibels was recorded and documented at a distance of 32 feet from the stage. That’s right at the boundary of the threshold of pain. Which I’m sure is what they were going for.

There are a variety of charts available that relate common noises to the decibel levels they could be expected to produce. For instance, a DC-9’s engines produce a sound level of about 120 decibels at takeoff or landing. Now, imagine if such a plane were to land at the aforementioned concert: would the sound level, at a given distance, be equal to those two decibel levels added together?

The answer, of course, is no, because we’re talking about sound pressure level. It’s not EXACTLY the same as fluid pressure, but a decent analogy is that, if you have an air compressor supplying your system with 100psig compressed air, turning on your other, identical air compressor won’t result in 200psig in your system.

I mention this for a couple of reasons. One; I’m a BIG fan of The Who, and I heard one of my favorite songs of theirs on the radio this morning: “You Better You Bet,” from their Face Dances album, which came out in 1981 and hence would not have been played at the 1976 Loudest Band concert, but I digress.

The other reason is because of a conversation I had with a caller about the sound levels produced by our Super Air Knives. The published sound pressure level is 69 dBA. “dB” is short for decibels; “A” means the unit is weighted to express the relative loudness of sounds as perceived by the human ear. Anyway, the caller was interested in knowing how much louder our longer Super Air Knives were than their shorter counterparts. The answer is, of course, they’re not louder…for the same reason that your second air compressor doesn’t double the air pressure in your system, which is the same reason that the fictional jet landing at the rock concert wouldn’t double the sound level.

Now, a couple of things to consider: the sound pressure levels that we publish were measured at a distance of 3 feet to the side of the Super Air Knife. Sound levels at a closer distance, and/or in front of or behind the Air Knife, will be different. Also, the Super Air Knife was blowing into free air. If the air flow is impinging on a surface, there will be a sound level associated with that as well. If it’s in excess of the 69 dBA that the Super Air Knife is producing, then that’s what your ears are going to be subject to.

All things considered, though, the Super Air Knife is INCREDIBLY quiet, considering the amount of air flow it’s producing. The science behind this has to do with what makes them so efficient with their use of compressed air: their entrainment ability. The Super Air Knife’s design allows it to use the primary compressed air flow to entrain enormous amount of air from the surrounding environment. This entrained air not only multiplies the resultant flow rate produced, but forms an attenuating boundary layer, which effectively reduces the sound level produced by the high velocity compressed air.

The Super Air Knife entrains air at a rate of 40:1, relative to its compressed air consumption.

We deal with several unique and challenging applications on a regular basis and many times we field a request that falls right into our expertise, compressed air savings!

I was recently contacted by a customer who was looking to reduce the compressed air consumption in their separator cleaning operation. The separator is continually cleaned by using compressed air through a header with a series of nozzles attached. Their current air consumption was roughly 720 SCFM and there were 2 headers per separator or 1,440 SCFM total for the process. (As you will see, that is ALOT of compressed air!) The headers cover a width of 36″ and blow through perforated sheet metal to remove fiber glass from clogging the holes. They were considering switching to a blower system but wanted to avoid large capital costs and engineering fees so they called EXAIR for assistance.

I recommended the customer use our 36″ Super Air Knife which would reduce their air consumption to 104.4 SCFM (@ 80PSIG) or roughly 615 SCFM per header.

Available from 3″ up to 108″ in aluminum, 303ss or 316ss construction.

Using the average of $ 0.25 per 1,000 SCFM, I calculated the following potential savings:

For this customer,these 36″ Super Air Knives will pay for themselves in less than 9 days!

This provided the customer with the compressed air savings they were hoping to achieve, plus saving the capital and engineering dollars to spend elsewhere in the plant. Not to mention saving the amount of valuable space they would need to dedicate to a blower system and maintenance required to keep the unit operational.

Based on the way our customer described the application and our knowledge of what it takes to solve an application successfully, this was another case of a customer providing significantly more compressed air than necessary to get the job done. The customer has ordered the units and is currently in the process of testing it under our Unconditional 30 Day Guarantee. To see how we can help optimize your current system, give us a call.

I visited my family in Kentucky, and we went to the spillway at Cave Run Lake in the Daniel Boone National Park. At the beginning of Licking River, there is a large pipe that drains from Cave Run Lake. Kentucky had quite a bit of rain and the lake was very full. The pressure from the lake was pushing lots of water through the drainage pipe. It emptied into a cement channel and then into the mouth of the river. As seen in the picture below, the water behaves violently as it exits the pipe and goes into the channel. This turbulent state is loud and chaotic, and you can see the waves traveling upstream. After the channel, the water transformed, and the river was quiet, calm and all flowing in the same direction. This helped me to create a visual on how compressed air must look.

From Channel to River

Turbulent Water from Pipe

Even though we cannot see compressed air, it follows the same rules as a fluid. Like the water coming out of the drainage pipe, the turbulence represents the flow of compressed air from an open pipe or copper tube. The noise was extremely loud and the water was traveling side to side and back on itself. You can see the inefficiency. But after the channel, you can see the transformation to a laminar state. EXAIR Super Air Knives and Super Air Nozzles do this with compressed air. The laminar flow of air is quiet, and it efficiently works together.

Turbulence is useful for mixing, but horrible for reducing noise and effective blowing, very similar to the violent action of water flowing from the drainage pipe. You can replace an open pipe with EXAIR air nozzles to achieve the same laminar flow. Then you can reduce the noise level, and the amount of compressed air being used. To get the most out of your compressed air system, the EXAIR Super Air Knives and Super Air Nozzles are the products to use. contact our Application Engineers now to discuss the amount of noise reduction and cost savings you can achieve by using EXAIR products.

When my sons were little boys, I would find myself looking forward to their teenage years, so they’d be more mature and I’d be able to relate to them better. Those of you with older kids may begin laughing now. My thinking was, I distinctly remember being thirteen. What I failed to recall was just exactly how peculiar I appeared to my parents (and they to me), and now, I’ve got the view from the other side.

In the interest of time and good taste, I’ll limit this discussion to the subject of food. I always liked (and still do like) ketchup almost as much as the french fries. Same for the “fixin’s” on a sandwich. In fact, as an adult, I’ve discovered a universal truth, that bacon or peanut butter can be used to improve the quality of ANY sandwich.

My sons, however, don’t feel this way at all. My fifteen year old won’t put anything but cheese (American cheese, at that) on a hamburger, and his thirteen year old brother won’t even do that. Curiously, the older one prefers cheese pizza, and the younger one will eat anything that used to be an animal on his. And neither one will put any sort of condiment or sauce on ANYTHING they eat. If it’s on their plate, it better not “have stuff on it.”

Our PVDF Super Air Knives provide the same highly efficient and quiet performance as their aluminum, 303SS, and 316SS counterparts – plus you can get a lot more “stuff” on them without damaging them.

Regardless of where you need to install it, or what kind of stuff you might get on it, EXAIR has a Super Air Knife that will hold up in your application. Give us a call, and we’ll find the right one for you.

Just today I spoke with a customer who is threading the ends of pipes and needs to blow the coolant and chips out of the threads. The pipes range from 4″ to 9 – 5/8″ Diameters. They are all threaded then fed into a trough and pushed down line to the next operation.

A machine with an out-feed roller conveyor similar to the pipe threading machine mentioned.

The photo above is not the exact machine but you can see where if this was used to process piping the different diameter pipes would all sit at the same level. One option could be to use a Super Air Wipe for this application but then the smaller diameters would not pass through the center of the Air Wipe, instead they would pass through the bottom half of the airflow which may not give optimal performance. Instead, I suggested to use 4 of our 6″ Super Air Knife kits and 2 of our Electronic Flow Control units.

I suggested that we make two pairs of knives for this blowoff setup by coupling two of the 6″ Super Air Knives together. Once they are coupled together like is shown above, we could mount the two coupled air knives vertically along the trough and blowing at a 45° angle toward the center of the conveyor. The plumbing of the two bottom knives will be to one EFC while the top two knives will be plumbed to the other. The sensors will then be set up at two different heights, lower knives to sense the bottom of the pipe and the upper knife sensor will be set just above the bottom 6″ knife.

The reason for using 4 – 6″ Super Air Knives and 2 EFCs instead of 2 – 12″ Super Air Knives and 1 EFC is to save the most compressed air possible. By enabling them to turn the top two 6″ Super Air Knives off automatically when they are running below a 6″ diameter pipe. Then when a larger pipe is processed the top knives will also kick on with the lower knives and provide a uniform blowoff of the product.

So if you have multiple sizes of product being processed on the same line and don’t think any one solution will work, contact us and see if we can’t come up with our own recipe.

If you’re even a casual, occasional reader of the EXAIR Blog, you know we write an awful lot about efficiency…namely, the ability of engineered products to conserve compressed air, while optimizing its effectiveness. Oftentimes, these blogs are inspired by a conversation we’ve had with a user of simple and inexpensive (but wasteful and unsafe) blow off devices, such as open-end tubing, or drilled pipes. The first thing the caller wants to talk about is the force produced by one of our products…will it be the same as what’s being currently used?

The quick answer is no. In fact, if you’re looking for maximum force, there’s no better way to get it than simply blowing compressed air out the end of an open pipe. This has to do with nothing more complicated that grade school science – converting the potential energy (due to the compression of the air) to kinetic energy (what happens when it’s put into motion.) See, with an open-end blow off, almost all of the potential energy is converted to force. Plain old brute force. And it works GREAT for blowing stuff around…the larger the opening, and the higher the supply pressure; the more air will flow, and faster. Thing is, to produce a good blow off, you don’t need maximum force.

EXAIR’s Intelligent Compressed Air Products are engineered to use some of that potential energy of the compressed air to entrain large amounts of “free” air from the surrounding environment. That’s the purpose of the jets recessed between the fins of our Super Air Nozzles, and the Coanda profile of our Air Knives, Air Wipes, & Air Amplifiers.

EXAIR Intelligent Compressed Air Products such as (left to right) the Air Wipe, Super Air Knife, Super Air Nozzle, and Air Amplifier are engineered to entrain enormous amounts of air from the surrounding environment.

These designs reduce the amount of compressed air that is used, which reduces the load on your air compressor, which makes everyone happy (OK, maybe not that happy, but pretty happy still.) They also mean that your blow offs will be quieter, and safer.

Perhaps, though, your application calls for the highest force that can only be achieved with an open-end blow off. If that’s the case, you can still meet OSHA compliance through the use of extra protective equipment, pressure relief valves, guarding devices, etc. But the costs of those measures can make the cost of engineered products pale in comparison, so I highly recommend you make sure of what you need.

If we can be of any assistance with that, give us a call. We can discuss your application, and get you the right tool for the job.